The present invention relates to a micro disc drive employing an arm level microactuator to enable reduction in the size of the disc drive and disc media and increased recording density on the disc media.
In order to increase the density of concentric data tracks on magnetic and polymeric recording discs, more precise radial positioning of the transducing head is required. Conventional disc drives, which are typically composed of stainless steel, accomplish head positioning by operating an actuator arm with a large-scale actuation motor, such as a voice coil motor, to radially position a head on a flexure at the end of the actuator arm. The large-scale motor lacks sufficient resolution to effectively accommodate high track-density discs. Thus, a high resolution head positioning mechanism, or microactuator, is necessary to accommodate the more densely spaced tracks.
One promising approach for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional lower resolution actuator motor, thereby effecting head positioning through dualstage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. These designs nearly universally involve the addition of a microactuator structure to a conventional disc drive assembly, so that traditional disc drive parts and disc media may continue to be used in the disc drive assembly. There are substantial technical challenges involved in implementing such microactuator designs to provide sufficiently large actuation forces, sufficiently stable and repeatable motions, and sufficiently high resolution to accommodate the high track densities that are desired. Many of these designs utilize some sort of piezoelectric device to cause an elastic deformation of a moving portion of the microactuator and thereby move the transducing head across tracks of the disc. While these solutions are effective to accommodate higher track densities in conventional disc drive systems, the extent of track density increase is limited by manufacturing tolerances, forming processes, piezoelectric material variations, and mechanical vibrations due to wire connections to the head or the flex circuit utilized by the disc drive. In addition, because these designs utilize conventional disc drive components, no meaningful size reduction in the disc drive can be achieved, despite the potential for such a reduction due to the high track densities recorded on the disc media that would make a reduction in the size of the disc media possible.
There is a need in the art for a miniaturized disc drive system. capable of accommodating extremely high track densities with sufficient actuation force and resolution, utilizing an assembly that is simple and inexpensive to manufacture.
The present invention is a micro disc drive assembly including a wafer-level actuator arm, a wafer-level suspension, and a head-carrying slider supported by the suspension over a rotatable disc. A microactuator motor is located between the actuator arm and the suspension, and is operable to move the suspension with respect to the actuator arm to position the head-carrying slider adjacent to a selected track of the rotatable disc. By forming the actuator arm and suspension at the wafer level, significant size reductions can be made, such that in an exemplary embodiment the actuator arm is no longer than about 10 millimeters. The reduced length of the actuator arm increases the stiffness of the arm and therefore increases the resonant frequency of the disc drive for seek operations. A main actuator may also be provided in one embodiment, also formed at the wafer level and including coils deposited on a wafer substrate, to coarsely position the actuator arm, suspension and head-carrying slider adjacent to the selected track of the rotatable disc. In another embodiment, a plurality of ganged actuator arms, suspensions and head-carrying sliders may be provided, with independent microactuator motors between each of the actuator arms and suspensions to finely position each of the head-carrying sliders.